Oil and grease wastewater are being produced in many industries such as oil refineries, petrochemicals, food industries, leather manufacturing, and steel industries. Grease, fat, and oil in wastewater of such industries must be removed before releasing it into the environment. In some cases, for example in petroleum refineries, crude oil, extracted from the wastewater, returns to that refinery again and in some refineries, the oil and fat extracted would be used in other fields such as fuels to produce energy. According to regulations in some countries, the standard amount of oil and fat in refinery wastewaters must be 10 mg/l, although some international standards allow for the amount of oil and fat in refinery wastewaters to be limited to 15 mg/l.
Currently, there are numerous conventional methods and systems, for example, wetland system, biological system, and chemical system, to be used for oily wastewater treatment. The conservation and profession costs are an important factor to choose the best method, so research and surveys have been done to find an efficient, economical, and especially wastewater treatment system that would be better for the environment. However, the conventional biological and chemical systems are expensive for treating oil and grease wastewater. The biological and chemical systems require maintenance and the process and operation are difficult and cumbersome for oil and greasy wastewater treatment. The existing systems are frequently failed and also clogged with biosolids. Further, the existing systems permit the influent to bypass the clogged region and pass substantially untreated to a downstream region.
Researches and surveys have been done to find an efficient and especially wastewater treatment system that suitable to the environment. The surveying details of
TABLE 1(PRIOR ART)Area ToSize (m)OrganicLoadTreatment(Width ×LoadRatioPlantLength)Planted Species(p.e.)(m2/p.e.)(1) Moesgård25 × 20Typha Latifolia1802.8Carex AcutiformisPhragmites Aust.(2) Hjordkær87 × 13Phragmites Aust.6001.9(3) Ingstrup 8.5 × 13.5Phragmites Aust. 523(4) Rugballegård 8 × 12Phragmites Aust.5-253.8-19(5) Lunderskov60 × 25Natural Wetland(200)(7.5)(6) Knudby19 × 19Phragmites Aust. 655.6(7) Borup30 × 48Phragmites Aust.2007.2(8) Kalø38 × 20Phragmites Aust.3002.5an existing wetland pilot for treating urban sewage as shown in Table. 1. The existing pilot is constructed with a horizontal flow and made of plastic. The survey is conducted on different existing plants, for example, mosegard, hjordkar, ingstrup, rugballegard, lunderskov, kundby, borup, and kalo at different time periods for measuring biochemical oxygen demand (BOD). The existing plants planted Typha latifolia, Carex acutiformis, and Phragmites Australis. The mosegard plant has an organic load corresponding to approximately 180 PE and area to load ratio is 2.8 m2/PE, the hjordkar has an organic load corresponding to approximately 600 PE and area to load ratio is 109 m2/PE, the ingstrup has an organic load corresponding to approximately 5 PE and area to load ratio is 23 m2/PE, the rugballegard has an organic load corresponding to approximately 5-25 PE and area to load ratio is 3.8-19 m2/PE, the lunderskov has an organic load corresponding to approximately 200 PE and area to load ratio is 7.5 m2/PE, the kundby has an organic load corresponding to approximately 65 PE and area to load ratio is 5.6 m2/PE, the borup has an organic load corresponding to approximately 200 PE and area to load ratio is 2.5 m2/PE.
Referring to Table. 2, treatment performances of the existing constructed wetlands at different time periods. The treating percentages of BOD, nitrogen, and phosphorus of the existing plants as shown in the Table. 2.
For example, the moesgard plant could remove 80% of the BOD, 30% of the nitrogen, and 38% of the phosphorus in the time period of August 84-October 85. The
TABLE 2(PRIOR ART)TreatmentBODTotal-NitrogenTotal-PhosphorusPlantPeriodInOut%InOut%InOut%MoesgårdAugust 1984-October 19851062280%453030%6.63.838%HjordkærJuly 1984-August 19851495466%412929%14.111.717%IngstrupJune 1984-September 19853681895%1121288%513.294%RugballegårdJune 1984-September 19854703982%893362%17.83.083%LunderskovSeptember 1984-September 1985522352%14653%4.22.445%KnudbyApril 1985-August 19851422976%382723%12.97.831%BorupApril 1985-August 1985983959%302325%11.710.418%KaløMarch 1985-August 1985753651%454010%9.38.811%hjordkar plant could remove 66% of the BOD, 29% of the nitrogen, and 17% of the phosphorus in the time period of July 84-August 85. The ingstrup plant could remove 95% of the BOD, 88% of the nitrogen, and 94% of the phosphorus in the time period of June 84-September 85. The rugballegard plant could remove 82% of the BOD, 62% of the nitrogen, and 83% of the phosphorus in the time period of June 84-September 85. The lunderskov plant could remove 52% of the BOD, 53% of the nitrogen, and 45% of the phosphorus in the time period of September 84-September 85. The knudby plant could remove 76% of the BOD, 23% of the nitrogen, and 31% of the phosphorus in the time period of September 84-September 85. The borup plant could remove 59% of the BOD, 25% of the nitrogen, and 18% of the phosphorus in the time period of April 84-August 85. The Kalo plant could remove 51% of the BOD, 10% of the nitrogen, and 11% of the phosphorus in the time period of September 84-September 85.
Referring to Table. 3, the treatment rate and results of the existing wetland system are disclosed. In this research two kinds of wetlands, horizontal and vertical, have been compared. Data of the compounds was separated into sections with and without aeration. The compounds, for example, benzene, BETX, TPH, and MTBE are summarized in Table. 3. Wetlands with horizontal are being found in Pompia, Crele, and south Greece and wetland with vertical flow rate being found in Gomati, Chalkidiki, and north Greece.
Referring to Table. 4, the treatment performance of subsurface flow constructed wetland is disclosed. The wetlands are constructed in this research as tanks, have the circular surface arears which are 0.75 square meters. This research lasted for 3 years in which simulated sewages have been used. In this research 2 kinds of plants, Cattail and Phragmites australis, and different media by different porosities, such as carbonate, ligneous, zeolite and bauxite have been used. Multiple parameters of the compounds include BOD, chemical oxygen demand (COD), total suspended solids (TSS), total kjeldahl nitrogen (TKN) and total phosphorus (TP) treating functions of subsurface flow constructed wetlands are summarized in Table. 4.
TABLE 3(PRIOR ART)AerationNo AerationCompoundWetland MulchNo MulchWetland MulchNo MulchBenzene518456317226BTEX356311257244TPH1058965725579MTBE64603522
TABLE 4(PRIOR ART)Pa-BODCODTSSTKNTPram-INSEFETEINSEFETEINSEFETEINSEFETEINSEFETEetermg 1−1%mg 1−1%mg 1−1%mg 1−1%mg 1−1%Aver-165397.794.44551001896.1191365.695.538251852.5139.16.253.1ageStd.314.01.31.0319.82.70.5405.40.80.93.41.71.74.81.51.31.14.7ErrorMin52112.086.5280442.092.7384.01.086.8178.04.023.14.82.31.610.6Max540601699.17981804099.6720901299.362362783.124222178.5# Of1414151417181817171818171718181717181817Data
The surface areas of wetlands with the horizontal flow are 4300 square meters and this number for wetlands with the vertical flow is 360 square meters for every 4 cells. The removal percentages (average, Std. error, minimum, and maximum) of the compounds of the wastewater are summarized in Table. 4.
Referring to Table. 5, the treatment performance of the vertical flow constructed wetland is disclosed. Pilots which are constructed in this research as tanks, have the circular surface areas which are 0.75 square meters. Multiple parameters of the compounds include BOD, COD, TSS, TKN, and TP treating functions of subsurface flow constructed wetlands are summarized in Table. 5.
TABLE 5(PRIOR ART)Pa-BODCODTSSTKNTDram-INSTEVSFTEINSTEVSFTEINSTEVSFTEINSTEVSFTEINSTEVSFTEetermg 1−1%mg 1−1%mg 1−1%mg 1−1%mg 1−1%Aver-4851933992626243628910772089957751147717.58.25.662ageStd.246111296260119315178447413847506209.03.93.122ErrorMin6210478238960812623075080317.54.32.424Max81935592100117146510610070602158471001872512710029.314.911.989# Of202019202020192020201920202019208888Data
Referring to Tables. 6, the specific details of the wetland pilot are disclosed. Various experimental parameters concerning operation, climate and produced biomass of each CW pilot-scale unit are summarized in the Tables. 6. At least 10 wetlands have been surveyed for 3 years. The diameters of these constructions were 0.82 meters and their heights were 1.5 meters. Tables. 6 are explaining the features of these wetlands, weather condition, the number of organic chemicals that were entered the systems and the time that the sewage need to set.
The inflow and outflow concentrations of compounds of the wastewater of at least ten existing wetlands are disclosed. The compounds of the wastewater include 5-days BOD, COD, TKN, ammonium-nitrogen (NH4.+—N), nitrite-nitrogen (NO2—N), TP, phosphates (PO43−.P), sulphate ion (SO4−2), pH, EC (μSjcm), dissolved oxygen (DO) (mg/L), and Tw (C). Statistical data of influent of effluent concentrations (mg/L), representative removal efficiencies (%), influent loading rate or areal load reduction (ALR; g/m2d) for each pollutant; and physicochemical parameters (mean deviation) of inflow and outflow concentrations of compounds of the wastewater of at least ten existing wetland systems are summarized.
TABLE 6(PRIOR ART)Operation ParametersConsideredWet/DryOrganic LoadingHydraulicClimatic ParametersParallelPeriodRate (g/m2)LoadingAir Temperature (° C.)Rainfall, mmYearUnits(Days)CODBODSRate(m/d)MeanMinMax(Days/Year)1 (October 2007-October 2008)42/6107.289.90.19516.2−6.639.5590.5(82) 2 (November 2008-October 2009)32/4124.9105.70.26316.2−2.538.0784.8(122)3(November 2009-October 2010)52/8219.6180.90.43916.5−9.437.1659.4(142)VFCW Unit CharacteristicsParameterW1W2W3W4W5W6W7W8W9W10Medium GravelCarbonateZeolite50% Carbonate50% CarbonateRiverbedCarbonate(Quarry)(Quarry)50% Zeolite50% BauxiteFine GravelCarbonateRiverbedCarbonate(Quarry)(Quarry)Plant SpeciesReedsCattailsUnplantedReedsAeration TubesYesNoYesSubstrate509080Thickness (cm)
The inflow and outflow concentrations of the wastewater of at least ten existing wetlands are disclosed. The inflow and outflow concentrations of the wastewater are observed at less than 15-degree centigrade weather temperature using existing wetland systems. Average effluent concentrations (mg/L), respective removal efficiencies (%) and areal load reduction (ALR; g/m2d) of compounds of the wastewater of at least ten existing wetland systems are summarized. The compounds of the wastewater include 5-days BOD, COD, TKN, ammonium-nitrogen (NH4.+—N), nitrite-nitrogen (NO2-N), TP, phosphates (PO43−.P), and sulphate ion (SO4−2).
The inflow and outflow concentrations of the wastewater of at least ten existing wetlands are disclosed. The inflow and outflow concentrations of the wastewater are observed at more than 15-degree centigrade weather temperature using existing wetland systems. Average effluent concentrations (mg/L), respective removal efficiencies (%) and areal load reduction (ALR; g/m2d) of compounds of the wastewater of at least ten existing wetland systems are summarized. The compounds of the wastewater include 5-days BOD, COD, TKN, ammonium-nitrogen (NH4.+—N), nitrite-nitrogen (NO2-N), TP, phosphates (PO43−.P), and sulphate ion (SO4−2).
Referring to FIG. 1A, a graph represents the treatment performance of the BOD (mg/L) compound of the effluent wastewater using the existing wetland systems during at least 3 years are summarized. Referring to FIG. 1B, the graph represents the treatment performance of the COD (mg/L) compound of the effluent wastewater using the existing wetland systems during at least 3 years are summarized. Referring to FIG. 1C, the graph represents the treatment performance of the TKN (mg/L) compound of the effluent wastewater using the existing wetland systems during at least 3 years are summarized.
Referring to FIG. 1D, the graph represents the treatment performance of the ammonium-nitrogen (NH4.+—N) (mg/L) compound of the effluent wastewater using the existing wetland systems during at least 3 years is summarized. Referring to FIG. 1E, the graph represents the treatment performance of the TP (mg/L) compound of the effluent wastewater using the existing wetland systems during at least 3 years is summarized. Referring to FIG. 1F, the graph represents the treatment performance of the phosphates (PO43−.P) (mg/L) compound of the effluent wastewater using the existing wetland systems during at least 3 years is summarized.
The survey has been conducted on different compounds or components of the different type of wastewaters. The different type of effluent wastewaters are generated from different type of plants include coke plant, oil refineries, pulp and paper tannery, pharmaceuticals laundry, organic chemistry plants, textile plants, distillery plants, winery plants, and brewery plants, soft drink plants, sugar mills, vegetable and food processing, meat processing, fish processing, starch processing, yeast processing, dairy/cheese factories, and olive oil mills. The different type of effluent wastewaters includes different compounds with different concentrations which are summarized. For example, the coke plant effluent includes 5-days of BOD ranges from 50-5300 (mg/L), COD ranges from 525-10,000 (mg/L), TSS ranges from 20-4500 (mg/L), NH4.+—N ranges from 200-550 (mg/L), TP is less than 1, and phenols ranges from 81-1200 (mg/L) are summarized.
Referring to Table. 7, the comparison between different wastewaters produced from different plants and mills is disclosed. The type of wastewater produced from, for example, a sugar mill, a dairy plant, a paper mill, brewery, laundry, tannery, cellulose (sulfite), and a yeast factory. The industrial wastewaters could be expressed in terms of population equivalent (PE) according to 5-days of BOD are summarized in the Table. 7. For example, the PE of the sugar mill ranges from 45-70, the PE of the dairy plant ranges from 40-230, the PE of the paper mill ranges from 200-900, the PE of the brewery ranges from 150-350, the PE of the laundry ranges from 350-900, the PE of the tannery ranges from 1000-5000, the PE of the cellulose (sulfite) ranges from 3000-5000, and the PE of yeast factory ranges from 5000-7000.
The survey has been conducted on polluted groundwater. The polluted
TABLE 7(PRIOR ART)Type of WastewaterUnitPESugar MillSugar Beet (1 t)45-70DairyMilk (1 m3) 40-230Paper MillPaper (1 t)200-900BreweryBeer (1 m3)150-350LaundryLaundry (1 t)350-900TanneryLeather (1 t)1000-5000Cellulose (Sulfite)Cellulose (1 t)3000-5000Yeast FactoryYeast (1 t)5000-7000groundwater characteristics and their concentrations are disclosed. The groundwater inflow includes different parameters. The parameters of the groundwater inflow are represented and summarized with average and standard deviations (±σ). For example, the average value of the parameter benzene ranges from 10.2±3.8 mg/L, MTBE ranges from 0.88±0.32 mg/L, toluene ranges from 0.002±0.001 mg/L, ethylbenzene ranges from 0.019±0.017, m-p-xylene ranges from 0.009±0.004 mg/L, o-xylene ranges from 0.008±0.003 mg/L, NH4+ ranges from 27.1±8.0 mg/L, NO3— ranges from 0.204±0.164 mg/L, NO2— is less than 0.010 mg/L, PO4−3 ranges from 1.80±0.74 mg/L, Fe+2 ranges from 3.14±0.71 mg/L, SO4−2 76.0±34.8 mg/L, Cl− ranges from 142.7±29.8 mg/L, Ca+2 ranges from 204.1±17.0 mg/L, K+ ranges from 10.6±1.3 mg/L, Na+ ranges from 143.1±23.4 mg/L, Mg+2 ranges from 45.7±3.2 mg/L, and Mn+2 ranges from 1.2±0.3 mg/L.
Referring to Table. 8, the duration of the experimental activities on groundwater is disclosed. This research has been done in different time periods and activities are summarized in the Table. 8. Sampling took place simultaneously in all beds include bed A (planted), bed B (unplanted), and bed C (planted). The beds A and B are received contaminated groundwater with injected phenol/m-cresol, and bed C receives contaminated groundwater without phenol/m-cresol.
TABLE 8(PRIOR ART)ExperimentalPhaseDateActivityPreliminary6 Aug.-24 Oct. 2012Phenol/m-cresol injection period(P1)11 field sampling campaignsMain (P2)8 Apr. 2013Field sampling(before injections period)P2a(Q =17 Apr.-5 Aug. 2013Phenol/m-cresol injection period11 L/h)14 field sampling campaignsP2b(Q = A,5 Aug.-23 Oct. 20132 field samplings (afterC: 11 L/h,30 Oct., 27 Nov. 2013injections period) ReedB: 22 L/h)11 Dec. 2013harvesting and Weighing
Referring to FIG. 2, the details of the existing constructed wetland pilot. The existing wetland pilot includes an opening to allow the influent into the wetland pilot. The existing wetland pilot includes coarse gravel, fine gravel (planted or unplanted), open water compartment, and another coarse gravel. The influent could pass via the coarse gravel to the fine gravel. After, the influent could also be passed via the open water compartment and the other coarse gravel to purify the influent and convert into an effluent. The existing wetland pilot is in length of 5.90 m. The coarse gravel has a length of 0.2 m, the fine gravel has a length of 4.5 m, and the open water compartment has a length of 1 m.
The survey has been conducted on M-cresol and phenol of the influent and effluent of the system. The M-cresol is an organic chemical compound that is counted as methyl phenols. Mostly, this compound is being used to produce other chemicals. Concentration of m-cresol and respective removal efficiencies of units A and B for the preliminary phase (P2; 14th August-24th October), the main phase (P2; duration of 8th April-23rd October), and the sub-phases P2a (8th April-5th August), and P2b (5th August-23rd October).
Referring to FIG. 3, the treatment performance of the existing wetland system in different phases is disclosed. The existing wetland system could treat phenol (mg/L) presented in the wastewater in different phases. The treatment performance could be changed according to the different phases during different time periods. For example, the preliminary phase (P1) is performed in one year and the main phase (P2) is performed a year later.
Referring to Table. 9, the concentrations of the inflow and outflow of the applied wastewater into the existing wetland system is disclosed. This system consists of two parallel wetlands that their dimensions are 0.5*6.1 meters. There's a summary of initial and final pollution density in the following Table. 9. The treatment efficiency of an FWS CW at the shell Norco refinery in St. Charles Parish, La., USA is summarized in the Table. 9. For the inflow, secondary wastewater was used. The parameters of the inflow and outflow includes aluminum, copper, iron, lead, manganese, zinc, TPH, ammonia, BOD, oil and grease, and TSS. For example, the aluminum presented in inflow and outflow include 738 mg/L and 102 mg/L respectively.
TABLE 9(PRIOR ART)InflowOutflowParameter(mgL−1)(mgL−1)Aluminum738102Copper22.415Iron2.50.3Lead10.52.2Manganese120898Zinc56686TPHa18.91.5Ammonia0.70.3BOD538.68.1Oil and Grease19.65.0TSS82.84.5
Referring to FIG. 4, a general theme of an existing constructed wetland is disclosed. The existing wetland constructed with an oil/water separator, a cascade aerator, free water surface (FWS) wetlands, and subsurface (SSF) wetlands. The oil and water in wastewater are separated using the oil/water separator. After, the wastewater could pass through the cascade aerator and to the FWS wetlands. The cascade aerator could uniformly distribute air in the wastewater and the FWS wetlands could reduce volatile compounds in the wastewater. Further, the wastewater could pass to the SSF wetlands to treat the effluents, and adds pre-treatment nutrients to the wastewater so as to enhance microbial growth therein for improving wastewater treatment.
Referring to Table. 10, the treatment performance of the constructed wetland in British petroleum is disclosed. The wastewater could include different compounds, for example, benzene, BTEX, and GRO. For example, the benzene in the wetland influent at the concentration level of 0.17 mg/L and in the wetland effluent of non-detect 0.01 mg/L. The BTEX in the wetland influent at the concentration level of 0.47 mg/L and in the wetland effluent at the concentration level of 0.0.1 mg/L (non-detect), and the GRO in the wetland influent at the concentration level of 2.02 mg/L and in the wetland effluent at concentration level of 0.05 mg/L.
TABLE 10(PRIOR ART)CompoundWetland InfluentWetland EffluentBenzene, mg/L0.17Non-detect (0.01)BTEX, mg/L0.47Non-detect (0.01)GRO, mg/L2.02Non-detect (0.05)
The conventional wetland system can be used commercially for efficient biological treatment of wastewater. It will also act as a better eco-friendly method when compared with other conventional biological treatment methods. The conventional wetland system has low structural costs compared to other conventional biological and chemical systems. However, the conventional wetland system requires a larger space compared to the other conventional systems. The conventional wetland systems are also used in oil and refinery industries. The wetland systems are constructed with the horizontal flow to treat wastewater produced from petroleum industries. The sewage flow is in DAF exit unit consists of an omitting percentage of BOD (98%), COD (93%), ammonia (84%), sulfides (100%), phenols (99%), oils and grease (99%).
U.S. Pat. No. 9,315,406 to Strano Sarah K., describes a wetland treatment system for treating wastewater includes a first zone comprising at least one anaerobic tank, and a second zone comprising at least one engineered wetland. It may also include a third zone comprising at least one bauxite residue cell. The engineered wetland includes media and vegetation (plants) which is aerated via an aeration system. The aeration system is aerated by directing air using pipes with a plurality of perforations in the engineered wetland, wherein the pipes are located at the bottom of the engineered wetland. The system includes a baffle configuration to distribute the flow of wastewater into the tank with at least one predetermined flow path at a surface overflow rate of at least 0.25 m/hr. However, the existing wetland systems require a large space for treating wastewater. Further, the existing wetland systems are limited to purify the violate compounds within the wastewater.
Herein forth, there is a need for an aerated wetland system used for oil refinery wastewater treatment by combining aerobic and anaerobic condition. There is also a need for an aerated wetland system to avoid clogging problems of the wastewater by increasing the speed at an entry of the system. There is also a need for an aerated wetland system. There is also a need for an aerated wetland system provided with irrigation tubes to improve the oxygen concentration levels in the wastewater.